It is known in the art that carbon black, an important ingredient in many rubber products, can be produced by pyrolytic decomposition of hydrocarbons. One of the most successful embodiments of this process is carried out by axially feeding a hydrocarbon feedstream into a tubular reactor along the axis and generating a spiraling flow of hot combustion gases around this feedstream. Whereas this process produces carbon black with desirable properties, a further increase in surface area as measured by tint for a given combination of air and hydrocarbon rates would prove beneficial economically and therefore would be desirable.